Estudo batimétrico sonográfico do estuário Guajará, Belém-Pa

Abstract

The Guajará Estuary, surrounding the city of Belém, encompasses the homonymous Bay and the confluence of the Guamá and Guajará-Açú rivers. Distant about 120 kilometers from the Atlantic Ocean, it has been studied in recent years, mainly regarding its hydrodynamic, physical and chemical parameters, in addition to the qualitative and quantitative distribution of the sediments present in the gutters. In this work, the recognition of the bottom morphology of this Estuary, through bathymetric and sonographic analysis, aimed to integrate new data to studies already carried out and to evaluate the influence of surface and bottom currents on the bed modeling. The use of the “Side Scan Sonar” proved to be very useful in identifying the bottom morphology and its relationship with the predominant action of tidal currents in the Guajará Estuary. It also demonstrated how sonograms can serve as a basis for comparing the different forms of resulting from local hydrodynamic variations. The Porto de Belém region, on the right bank of the Guajará Bay, is frequently subjected to dredging operations. This area partially protected from tidal currents is a site of intense and constant deposition of sediments, resulting in an accelerated silting of the channel and therefore making dredging indispensable, under penalty of compromising the operation of that Port. These operations make any attempt to establish a morphological pattern there and relate it to the action of the currents extremely difficult. The circulation of water in the Guajará Estuary, promoted by variations in tidal currents and river discharge, results in the upstream waters predominantly falling on its left bank, developing great depths in this area and progressive erosion on the eastern side of Ilha das Onças. . In the northern portion of the Ilha das Onças Channel, in the deeper zones, the lineations of currents and the “sand waves” field are the most frequent and important sedimentary bottom features in the interpretation of the hydrodynamic conditions of the Estuary.